# Fetch all keys based on some pattern

**URL:** <https://discuss.aerospike.com/t/fetch-all-keys-based-on-some-pattern/10203>\
**Category:** Query & Indexing\
**Tags:** key, query\
**Created:** [May 16, 2023, 8:26pm UTC](https://discuss.aerospike.com/t/fetch-all-keys-based-on-some-pattern/10203 "2023-05-16T20:26:38Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![unverifieduser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/unverifieduser/32/2079_2.png) [@unverifieduser](https://discuss.aerospike.com/u/unverifieduser)\
**Post date:** [May 16, 2023, 8:26pm UTC](https://discuss.aerospike.com/t/fetch-all-keys-based-on-some-pattern/10203/1 "2023-05-16T20:26:39Z")

</div>

i have thousands of records on namepace:set.

keys are of pattern: lastname/firstname/state/zip example: brown/chris/fl/32514

i want to get all keys based on the pattern “\*/chris/\*/32514” and perform delete operation on the resulting keys. i can do a scanAll but that is very expensive operation. i have seen many posts but couldn’t find a solution. please suggest on how can i achieve this.

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<div class="post-metadata">

**Author:** ![aanderson](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/aanderson/32/2064_2.png) [@aanderson](https://discuss.aerospike.com/u/aanderson)\
**Post date:** [May 18, 2023, 6:30pm UTC](https://discuss.aerospike.com/t/fetch-all-keys-based-on-some-pattern/10203/2 "2023-05-18T18:30:36Z")

</div>

Hey @unverifieduser, welcome to the forum!

I’m assuming you’re talking about the records key, but you could follow the same setup for a map key as well, with a little extra setup.

To achieve this you would need to do a full scan, or secondary index query, but you could utilize a [filter expression](https://docs.aerospike.com/server/guide/expressions), [`RegexCompare`](https://docs.aerospike.com/server/guide/expressions/comparison#cmp_regex) to be exact, to compare the key with the pattern. One caveat to this, **the records would need to have been written with the [`sendKey` write policy](https://developer.aerospike.com/client/usage/atomic/create#policies) set to true**.

Here is a code sample, in Go, that walks through writing a record and then using a query with an expression filter to return based on a pattern to match the key. You could change things up to utilize a [background query](https://developer.aerospike.com/client/usage/queries/background) for the deletion.

You can drop this code directly into the [sandbox](https://developer.aerospike.com) on our Developer Hub as well. Just select Go as the language and hit `Connect`, the paste and run this on the blank code tab. Hope that helps!

```auto
// Import Aerospike client library
import (
    "log"
    as "github.com/aerospike/aerospike-client-go/v6" 
)

func writeData() {
    client, errClient := as.NewClient("127.0.0.1", 3000)
    if errClient != nil {
        log.Printf("Error: %s", errClient)
    }
    
    // Close the connection to the server
    defer client.Close()
    
    // Initialize a write policy
    policy := as.NewWritePolicy(0,0)
    policy.SendKey = true

    // Create a key in namespace "sandbox" and set "ufodata"
    key, errKey := as.NewKey("sandbox", "ufodata", "myKeyString")
    if errKey != nil {
        log.Printf("Error: %s", errKey)
        return
    }

    // Create the bins as Bin("binName", value)
    myBin := as.NewBin("myBin", "we did it!")

    // Write the record to Aerospike
    errWrite := client.PutBins(policy, key, myBin)
    if errWrite != nil {
        log.Printf("Error: %s", errWrite)
        return
    }
    
    log.Println("One record added")
}

func getData(){
    
    client, errClient := as.NewClient("127.0.0.1", 3000)
    if errClient != nil {
        log.Printf("Error: %s", errClient)
        return
    }
    
    // Close the connection to the server
    defer client.Close()
    
    // Create query policy
    queryPolicy := as.NewQueryPolicy()
    queryPolicy.FilterExpression = as.ExpRegexCompare(
        ".*Str.*",
        as.ExpRegexFlagICASE,
        as.ExpKey(as.ExpTypeSTRING))

    // Create statement
    stmt := as.NewStatement("sandbox", "ufodata")

    // Execute the query
    recordSet, err := client.Query(queryPolicy, stmt)
    if err != nil {
        log.Printf("Error: %s", err)
        return
    }

    // Get the results
    for records := range recordSet.Results() {
        if records != nil { 
            // Do something
            log.Printf("Record: %v \n", records.Record.Bins)
        }
    }

    recordSet.Close()
}

func main() {
    writeData()
    getData()
}

```

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<div class="post-metadata">

**Author:** ![unverifieduser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/unverifieduser/32/2079_2.png) [@unverifieduser](https://discuss.aerospike.com/u/unverifieduser)\
**Post date:** [May 19, 2023, 7:00pm UTC](https://discuss.aerospike.com/t/fetch-all-keys-based-on-some-pattern/10203/3 "2023-05-19T19:00:59Z")

</div>

thanks for the solution but, i was looking mostly to get only the keys and not records. is that possible?

if getting only keys is not possible, can i

1. create & use secondary index for filtering without any performance issues? my app does a lot of saving .
2. store my key in a seperate bin and do a delete operation with matching keys?

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<div class="post-metadata">

**Author:** ![aanderson](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/aanderson/32/2064_2.png) [@aanderson](https://discuss.aerospike.com/u/aanderson)\
**Post date:** [May 22, 2023, 7:07pm UTC](https://discuss.aerospike.com/t/fetch-all-keys-based-on-some-pattern/10203/4 "2023-05-22T19:07:32Z")

</div>

You could update the query policy with:

```auto
queryPolicy.IncludeBinData = false

```

to the example above to only return metadata.

The only way to create a secondary index on the key would be to store it in a bin within the record. You could also explore creating a [set index](https://docs.aerospike.com/server/architecture/set-indexes), if you are storing your data in a [set](https://docs.aerospike.com/server/architecture/data-model#sets), to possibly make querying the set more efficient.

If you are only looking to delete records with a key that matches a defined pattern, then as I said in my other response, you could use the query and filter expression as above, but execute as a [background query](https://docs.aerospike.com/server/guide/scan#background-read-write-query) that deletes the matching records. This returns only a `task` to track the query status, and would run asynchronously on the server. You can see [code samples](https://developer.aerospike.com/client/usage/queries/background) for background queries on the Developer Hub.